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Bernaola-Galván P, Carpena P, Gómez-Martín C, Oliver JL. Compositional Structure of the Genome: A Review. BIOLOGY 2023; 12:849. [PMID: 37372134 DOI: 10.3390/biology12060849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023]
Abstract
As the genome carries the historical information of a species' biotic and environmental interactions, analyzing changes in genome structure over time by using powerful statistical physics methods (such as entropic segmentation algorithms, fluctuation analysis in DNA walks, or measures of compositional complexity) provides valuable insights into genome evolution. Nucleotide frequencies tend to vary along the DNA chain, resulting in a hierarchically patchy chromosome structure with heterogeneities at different length scales that range from a few nucleotides to tens of millions of them. Fluctuation analysis reveals that these compositional structures can be classified into three main categories: (1) short-range heterogeneities (below a few kilobase pairs (Kbp)) primarily attributed to the alternation of coding and noncoding regions, interspersed or tandem repeats densities, etc.; (2) isochores, spanning tens to hundreds of tens of Kbp; and (3) superstructures, reaching sizes of tens of megabase pairs (Mbp) or even larger. The obtained isochore and superstructure coordinates in the first complete T2T human sequence are now shared in a public database. In this way, interested researchers can use T2T isochore data, as well as the annotations for different genome elements, to check a specific hypothesis about genome structure. Similarly to other levels of biological organization, a hierarchical compositional structure is prevalent in the genome. Once the compositional structure of a genome is identified, various measures can be derived to quantify the heterogeneity of such structure. The distribution of segment G+C content has recently been proposed as a new genome signature that proves to be useful for comparing complete genomes. Another meaningful measure is the sequence compositional complexity (SCC), which has been used for genome structure comparisons. Lastly, we review the recent genome comparisons in species of the ancient phylum Cyanobacteria, conducted by phylogenetic regression of SCC against time, which have revealed positive trends towards higher genome complexity. These findings provide the first evidence for a driven progressive evolution of genome compositional structure.
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Affiliation(s)
- Pedro Bernaola-Galván
- Department of Applied Physics II and Institute Carlos I for Theoretical and Computational Physics, University of Málaga, 29071 Málaga, Spain
| | - Pedro Carpena
- Department of Applied Physics II and Institute Carlos I for Theoretical and Computational Physics, University of Málaga, 29071 Málaga, Spain
| | - Cristina Gómez-Martín
- Department of Pathology, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
- Department of Genetics, Faculty of Sciences, 18071 and Laboratory of Bioinformatics, Institute of Biotechnology, Center of Biomedical Research, University of Granada, 18100 Granada, Spain
| | - Jose L Oliver
- Department of Genetics, Faculty of Sciences, 18071 and Laboratory of Bioinformatics, Institute of Biotechnology, Center of Biomedical Research, University of Granada, 18100 Granada, Spain
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Reye G, Huang X, Haupt LM, Murphy RJ, Northey JJ, Thompson EW, Momot KI, Hugo HJ. Mechanical Pressure Driving Proteoglycan Expression in Mammographic Density: a Self-perpetuating Cycle? J Mammary Gland Biol Neoplasia 2021; 26:277-296. [PMID: 34449016 PMCID: PMC8566410 DOI: 10.1007/s10911-021-09494-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 07/05/2021] [Indexed: 12/23/2022] Open
Abstract
Regions of high mammographic density (MD) in the breast are characterised by a proteoglycan (PG)-rich fibrous stroma, where PGs mediate aligned collagen fibrils to control tissue stiffness and hence the response to mechanical forces. Literature is accumulating to support the notion that mechanical stiffness may drive PG synthesis in the breast contributing to MD. We review emerging patterns in MD and other biological settings, of a positive feedback cycle of force promoting PG synthesis, such as in articular cartilage, due to increased pressure on weight bearing joints. Furthermore, we present evidence to suggest a pro-tumorigenic effect of increased mechanical force on epithelial cells in contexts where PG-mediated, aligned collagen fibrous tissue abounds, with implications for breast cancer development attributable to high MD. Finally, we summarise means through which this positive feedback mechanism of PG synthesis may be intercepted to reduce mechanical force within tissues and thus reduce disease burden.
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Affiliation(s)
- Gina Reye
- School of Biomedical Sciences, Gardens Point, Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia
- Translational Research Institute, Woolloongabba, QLD, Australia
| | - Xuan Huang
- School of Biomedical Sciences, Gardens Point, Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia
- Translational Research Institute, Woolloongabba, QLD, Australia
| | - Larisa M Haupt
- Centre for Genomics and Personalised Health, Genomics Research Centre, School of Biomedical Sciences, Faculty of Health, Institute of Health and Biomedical Innovation, Queensland University of Technology (QUT), 60 Musk Ave, Kelvin Grove, QLD, 4059, Australia
| | - Ryan J Murphy
- School of Mathematical Sciences, Gardens Point, Queensland University of Technology (QUT), Kelvin Grove, QLD, Australia
| | - Jason J Northey
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Erik W Thompson
- School of Biomedical Sciences, Gardens Point, Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia
- Translational Research Institute, Woolloongabba, QLD, Australia
| | - Konstantin I Momot
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - Honor J Hugo
- School of Biomedical Sciences, Gardens Point, Queensland University of Technology (QUT), Kelvin Grove, QLD, 4059, Australia.
- Translational Research Institute, Woolloongabba, QLD, Australia.
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Bernardi G. The "Genomic Code": DNA Pervasively Moulds Chromatin Structures Leaving no Room for "Junk". Life (Basel) 2021; 11:342. [PMID: 33924668 PMCID: PMC8070607 DOI: 10.3390/life11040342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/06/2021] [Accepted: 04/07/2021] [Indexed: 02/07/2023] Open
Abstract
The chromatin of the human genome was analyzed at three DNA size levels. At the first, compartment level, two "gene spaces" were found many years ago: A GC-rich, gene-rich "genome core" and a GC-poor, gene-poor "genome desert", the former corresponding to open chromatin centrally located in the interphase nucleus, the latter to closed chromatin located peripherally. This bimodality was later confirmed and extended by the discoveries (1) of LADs, the Lamina-Associated Domains, and InterLADs; (2) of two "spatial compartments", A and B, identified on the basis of chromatin interactions; and (3) of "forests and prairies" characterized by high and low CpG islands densities. Chromatin compartments were shown to be associated with the compositionally different, flat and single- or multi-peak DNA structures of the two, GC-poor and GC-rich, "super-families" of isochores. At the second, sub-compartment, level, chromatin corresponds to flat isochores and to isochore loops (due to compositional DNA gradients) that are susceptible to extrusion. Finally, at the short-sequence level, two sets of sequences, GC-poor and GC-rich, define two different nucleosome spacings, a short one and a long one. In conclusion, chromatin structures are moulded according to a "genomic code" by DNA sequences that pervade the genome and leave no room for "junk".
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Affiliation(s)
- Giorgio Bernardi
- Science Department, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy; ; Tel.: +39-33-540-5892
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
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Spreafico M, Mangano E, Mazzola M, Consolandi C, Bordoni R, Battaglia C, Bicciato S, Marozzi A, Pistocchi A. The Genome-Wide Impact of Nipblb Loss-of-Function on Zebrafish Gene Expression. Int J Mol Sci 2020; 21:E9719. [PMID: 33352756 PMCID: PMC7766774 DOI: 10.3390/ijms21249719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/31/2022] Open
Abstract
Transcriptional changes normally occur during development but also underlie differences between healthy and pathological conditions. Transcription factors or chromatin modifiers are involved in orchestrating gene activity, such as the cohesin genes and their regulator NIPBL. In our previous studies, using a zebrafish model for nipblb knockdown, we described the effect of nipblb loss-of-function in specific contexts, such as central nervous system development and hematopoiesis. However, the genome-wide transcriptional impact of nipblb loss-of-function in zebrafish embryos at diverse developmental stages remains under investigation. By RNA-seq analyses in zebrafish embryos at 24 h post-fertilization, we examined genome-wide effects of nipblb knockdown on transcriptional programs. Differential gene expression analysis revealed that nipblb loss-of-function has an impact on gene expression at 24 h post fertilization, mainly resulting in gene inactivation. A similar transcriptional effect has also been reported in other organisms, supporting the use of zebrafish as a model to understand the role of Nipbl in gene regulation during early vertebrate development. Moreover, we unraveled a connection between nipblb-dependent differential expression and gene expression patterns of hematological cell populations and AML subtypes, enforcing our previous evidence on the involvement of NIPBL-related transcriptional dysregulation in hematological malignancies.
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Affiliation(s)
- Marco Spreafico
- Department of Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, LITA, Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (M.S.); (M.M.); (C.B.); (A.M.)
| | - Eleonora Mangano
- Institute of Biomedical Technologies, Italian National Research Council (ITB-CNR), Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (E.M.); (C.C.); (R.B.)
| | - Mara Mazzola
- Department of Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, LITA, Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (M.S.); (M.M.); (C.B.); (A.M.)
| | - Clarissa Consolandi
- Institute of Biomedical Technologies, Italian National Research Council (ITB-CNR), Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (E.M.); (C.C.); (R.B.)
| | - Roberta Bordoni
- Institute of Biomedical Technologies, Italian National Research Council (ITB-CNR), Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (E.M.); (C.C.); (R.B.)
| | - Cristina Battaglia
- Department of Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, LITA, Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (M.S.); (M.M.); (C.B.); (A.M.)
| | - Silvio Bicciato
- Department of Life Sciences, University of Modena and Reggio-Emilia, Via G. Campi 287, 41125 Modena, Italy;
| | - Anna Marozzi
- Department of Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, LITA, Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (M.S.); (M.M.); (C.B.); (A.M.)
| | - Anna Pistocchi
- Department of Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, LITA, Via Fratelli Cervi 93, Segrate, 20090 Milano, Italy; (M.S.); (M.M.); (C.B.); (A.M.)
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Ayad LAK, Dourou AM, Arhondakis S, Pissis SP. IsoXpressor: A Tool to Assess Transcriptional Activity within Isochores. Genome Biol Evol 2020; 12:1573-1578. [PMID: 32857856 DOI: 10.1093/gbe/evaa171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2020] [Indexed: 01/20/2023] Open
Abstract
Genomes are characterized by large regions of homogeneous base compositions known as isochores. The latter are divided into GC-poor and GC-rich classes linked to distinct functional and structural properties. Several studies have addressed how isochores shape function and structure. To aid in this important subject, we present IsoXpressor, a tool designed for the analysis of the functional property of transcription within isochores. IsoXpressor allows users to process RNA-Seq data in relation to the isochores, and it can be employed to investigate any biological question of interest for any species. The results presented herein as proof of concept are focused on the preimplantation process in Homo sapiens (human) and Macaca mulatta (rhesus monkey).
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Affiliation(s)
| | | | | | - Solon P Pissis
- CWI, Amsterdam, The Netherlands.,Vrije Universiteit, Amsterdam, The Netherlands
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Bernardi G. The Genomic Code: A Pervasive Encoding/Molding of Chromatin Structures and a Solution of the "Non-Coding DNA" Mystery. Bioessays 2019; 41:e1900106. [PMID: 31701567 DOI: 10.1002/bies.201900106] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/07/2019] [Indexed: 12/15/2022]
Abstract
Recent investigations have revealed 1) that the isochores of the human genome group into two super-families characterized by two different long-range 3D structures, and 2) that these structures, essentially based on the distribution and topology of short sequences, mold primary chromatin domains (and define nucleosome binding). More specifically, GC-poor, gene-poor isochores are low-heterogeneity sequences with oligo-A spikes that mold the lamina-associated domains (LADs), whereas GC-rich, gene-rich isochores are characterized by single or multiple GC peaks that mold the topologically associating domains (TADs). The formation of these "primary TADs" may be followed by extrusion under the action of cohesin and CTCF. Finally, the genomic code, which is responsible for the pervasive encoding and molding of primary chromatin domains (LADs and primary TADs, namely the "gene spaces"/"spatial compartments") resolves the longstanding problems of "non-coding DNA," "junk DNA," and "selfish DNA" leading to a new vision of the genome as shaped by DNA sequences.
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Affiliation(s)
- Giorgio Bernardi
- Science Department, Roma Tre University, Viale Marconi 446, 00146, Rome, Italy
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy
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Jabbari K, Chakraborty M, Wiehe T. DNA sequence-dependent chromatin architecture and nuclear hubs formation. Sci Rep 2019; 9:14646. [PMID: 31601866 PMCID: PMC6787200 DOI: 10.1038/s41598-019-51036-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 09/18/2019] [Indexed: 02/08/2023] Open
Abstract
In this study, by exploring chromatin conformation capture data, we show that the nuclear segregation of Topologically Associated Domains (TADs) is contributed by DNA sequence composition. GC-peaks and valleys of TADs strongly influence interchromosomal interactions and chromatin 3D structure. To gain insight on the compositional and functional constraints associated with chromatin interactions and TADs formation, we analysed intra-TAD and intra-loop GC variations. This led to the identification of clear GC-gradients, along which, the density of genes, super-enhancers, transcriptional activity, and CTCF binding sites occupancy co-vary non-randomly. Further, the analysis of DNA base composition of nucleolar aggregates and nuclear speckles showed strong sequence-dependant effects. We conjecture that dynamic DNA binding affinity and flexibility underlay the emergence of chromatin condensates, their growth is likely promoted in mechanically soft regions (GC-rich) of the lowest chromatin and nucleosome densities. As a practical perspective, the strong linear association between sequence composition and interchromosomal contacts can help define consensus chromatin interactions, which in turn may be used to study alternative states of chromatin architecture.
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Affiliation(s)
- Kamel Jabbari
- Institute for Genetics, Biocenter Cologne, University of Cologne, Zülpicher Straße 47a, 50674, Köln, Germany.
| | - Maharshi Chakraborty
- Institute for Genetics, Biocenter Cologne, University of Cologne, Zülpicher Straße 47a, 50674, Köln, Germany
| | - Thomas Wiehe
- Institute for Genetics, Biocenter Cologne, University of Cologne, Zülpicher Straße 47a, 50674, Köln, Germany
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Pezzotta A, Mazzola M, Spreafico M, Marozzi A, Pistocchi A. Enigmatic Ladies of the Rings: How Cohesin Dysfunction Affects Myeloid Neoplasms Insurgence. Front Cell Dev Biol 2019; 7:21. [PMID: 30873408 PMCID: PMC6400976 DOI: 10.3389/fcell.2019.00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/05/2019] [Indexed: 12/04/2022] Open
Abstract
The genes of the cohesin complex exert different functions, ranging from the adhesion of sister chromatids during the cell cycle, DNA repair, gene expression and chromatin architecture remodeling. In recent years, the improvement of DNA sequencing technologies allows the identification of cohesin mutations in different tumors such as acute myeloid leukemia (AML), acute megakaryoblastic leukemia (AMKL), and myelodysplastic syndromes (MDS). However, the role of cohesin dysfunction in cancer insurgence remains elusive. In this regard, cells harboring cohesin mutations do not show any increase in aneuploidy that might explain their oncogenic activity, nor cohesin mutations are sufficient to induce myeloid neoplasms as they have to co-occur with other causative mutations such as NPM1, FLT3-ITD, and DNMT3A. Several works, also using animal models for cohesin haploinsufficiency, correlate cohesin activity with dysregulated expression of genes involved in myeloid development and differentiation. These evidences support the involvement of cohesin mutations in myeloid neoplasms.
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Affiliation(s)
- Alex Pezzotta
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy
| | - Mara Mazzola
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy
| | - Marco Spreafico
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy
| | - Anna Marozzi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy
| | - Anna Pistocchi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milan, Italy
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